Background

Extracts of Hypericum perforatum L. (St. John's wort) have been recommended traditionally for a wide range of medical conditions. The most common modern-day use of St. John's wort is the treatment of depression. Numerous studies report St. John's wort to be more effective than placebo and equally effective as tricyclic antidepressant drugs in the short-term treatment of mild-to-moderate major depression (1-3 months). It is not clear if St. John's wort is as effective as selective serotonin reuptake inhibitor (SSRI) antidepressants such as sertraline (Zoloft®).

Recently, controversy has been raised by two high-quality trials of St. John's wort for major depression that did not show any benefits. However, due to problems with the designs of these studies, they cannot be considered definitive. Overall, the scientific evidence supports the effectiveness of St. John's wort in mild-to-moderate major depression. The evidence in severe major depression remains unclear.

St. John's wort can cause many serious interactions with prescription drugs, herbs, or supplements. Therefore, people using any medications should consult their healthcare providers including their pharmacist prior to starting therapy.

Evidence

DISCLAIMER:
These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

Depressive disorder (mild-to-moderate):
St. John's wort has been extensively studied in Europe over the last two decades, with more recent research in the United States. Short-term studies (1-3 months) suggest that St. John's wort is more effective than placebo (sugar pill), and equally effective as tricyclic antidepressants (TCAs) in the treatment of mild-to-moderate major depression. Comparisons to the more commonly prescribed selective serotonin reuptake inhibitor (SSRI) antidepressants, such as fluoxetine (Prozac®) or sertraline (Zoloft®), are more limited. However, other data suggest that St. John's wort may be just as effective as SSRIs with fewer side effects. Safety concerns exist as with most conventional and complementary therapies.
Grade: A

Anxiety disorder:
Overall, there is currently not enough evidence to recommend St. John's wort for the primary treatment of anxiety disorders.
Grade: C

Atopic dermatitis:
Early study of hypericum-cream in the topical treatment of mild to moderate atopic dermatitis shows positive results. Further studies are needed before a firm recommendation can be made.
Grade: C

Depressive disorder (severe):
Studies of St. John's wort for severe depression have not provided clear evidence of effectiveness.
Grade: C

Nerve pain:
Early study shows that St. John's wort may help neuropathic (nerve) pain. Further research is needed to confirm these results.
Grade: C

Obsessive-compulsive disorder (OCD):
There are a few reported cases of possible benefits of St. John's wort in patients with obsessive-compulsive disorder (OCD). Currently there is not enough scientific evidence to recommend St. John's wort for this condition.
Grade: C

Peri-menopausal symptoms:
There is currently not enough scientific evidence to recommend St. John's wort for this indication.
Grade: C

Seasonal affective disorder (SAD):
Despite some promising early data, there is currently not enough evidence to recommend St. John's wort for depressive disorder with seasonal pattern or Seasonal Affective Disorder (SAD).
Grade: C

Somatoform disorders:
Somatoform disorders show physical symptoms that cannot be attributed to organic disease and appear to be of psychic origin. Early evidence shows that St. John's wort may help with somatoform disorders. Further research is needed to confirm these results.
Grade: C

Human immunodeficiency virus (HIV):
Anti-viral effects of St. John's wort have been observed in laboratory studies, but were not found in one human study. Multiple reports of significant adverse effects and interactions with drugs used for HIV/AIDS, including protease inhibitors (PIs) and non-nucleoside reverse transcriptase inhibitors (NNRTIs), suggest that patients being treated for HIV/AIDS should avoid this herb. Therefore, there is evidence to recommend against using St. John's wort in the treatment of patients with HIV/AIDS.
Grade: D

Social phobia:
Results of early study on the efficacy of St. John's wort in social phobia do not show benefit. More study is needed to confirm these findings.
Grade: D